(a) Field of the Invention
The present invention relates to a liquid crystal display and a manufacturing method thereof.
(b) Description of the Related Art
A liquid crystal display is one of widely used types of flat panel displays. The liquid crystal display includes two display panels containing field generating electrodes such as pixel electrodes and a common electrode. A liquid crystal layer is interposed between the display panels. Voltages are applied to the field generating electrodes to generate an electric field in the liquid crystal layer. The electric field determines the tilt angles of the liquid crystal molecules. The tilt angles control the polarization of incident light so as to form a desired image.
In many liquid crystal displays, the pixel electrodes are located in one of the panels and the common electrode is located in the other panel.
A liquid crystal display may also include color filters made of an organic material containing pigments for color display. If the color filters are located in the different panel than the pixel electrodes, the pixel electrodes may be undesirably misaligned with the color filters. To solve this problem, a color filter on array (CoA) structure has been developed in which the pixel electrodes and the color filters are formed in the same display panel. In addition to the color filters and the pixel electrodes, such display panel contains signal lines (such as gate lines and data lines) used to provide voltages to the pixel electrodes and also contains switching elements for controllably providing these voltages to the pixel electrodes.
Such display panel is formed using a number of thin films including one or more insulating layers, one or more semiconductor layers, and a number of conductive layers for the gate lines and the data lines. These thin films are patterned by photolithographic processes using a number of optical masks. Use of each mask increases the process time and complexity because use of each mask involves photoresist deposition, exposure, developing, and cleaning. Accordingly, it is desirable to reduce the number of masks required.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and may therefore contain information that does not form prior art for this patent application.